Tuberculosis still is a serious bacterial disease worldwide, and not only treatment methods but also diagnostic methods therefor are extremely important. A final diagnosis as to the tuberculosis infection is made by carrying out a culture method. However, since tubercule bacilli have an extremely slow growth rate, the establishment of a preliminary diagnostic method to be performed prior to the culture method has been desired. As such a preliminary diagnostic method, a method using a polymerase chain reaction (PCR) method is attracting attention. In this method, a primer specific to a gene of a tubercule bacillus is used to amplify a gene of the tubercule bacillus, if any, so that it can be detected, thereby enabling the presence or absence of the tubercule bacillus to be determined.
In the above-described preliminary diagnostic method using the PCR method, extracting the gene by lysing the tubercule bacillus is necessary as a pretreatment. Examples of conventional lysis methods include chemical methods using organic solvents or the like and physical methods using ultrasonic waves or repeating freezing and thawing. However, since tubercule bacilli have a high cell-wall lipid content, such conventional lysis methods cannot extract genes sufficiently. In order to achieve sufficient gene extraction, it is necessary to make the treatment conditions severer, which requires the use of a special device and/or a special reagent. Besides, this may result in a longer treatment period and a more complicated operation. Such problems with lysing are not specific to tubercule bacilli and relate to the entire acid-fast bacteria group including the tubercule bacilli.